This invention relates to an improved process for phosphate beneficiation. In particular this invention relates to the use as a collector of N-aminoethylpiperazine condensed with a fatty acid or fatty acid ester in the flotation of siliceous material from phosphate.
In the present commercial beneficiation of siliceous phosphate ores, a deslimed and sized phosphate ore is conditioned with and then floated by a fatty acid collector and fuel oil reagent in an aerated aqueous solution at a pH of at least about 8. This flotation process produces a low-grade phosphate concentrate containing from about 40 to 65 weight percent bone phosphate of lime (BPL). The "rougher float concentrate" from the aforementioned flotation is blunged with acid to remove fatty acid collector coatings and the phosphate is further concentrated by flotation of residual silica from the concentrate with a so-called cationic amine collector.
U.S. Pat. No. 2,278,060 teaches that the reaction product of a polyalkylenepolyamine with a fatty acid, a fatty acid glyceride or other fatty acid esters, as well as their corresponding water-soluble salts, can be used as cationic amine collectors. U.S. Pat. Nos. 2,278,107; 2,312,387; 2,322,201; and 2,710,856 also disclose the use of reaction products of a polyalkylenepolyamine with a fatty acid, alone or in combination with other flotation agents, to effect the flotation of silica from phosphate. U.S. Pat. No. 2,222,728 discloses that certain amine compounds bearing a hydrocarbon chain of six or more carbon atoms are useful as cationic amine collectors.
The prior art cationic amine collectors are effective in beneficiating phosphate ore. However, the demand for the polyethylenepolyamines in alternative, less cost-sensitive uses has resulted in a steady escalation in the price of the prior art cationic amine collectors. The increasing price has spurred a search in the phosphate industry for a flotation agent possessing greater cost-effectiveness. Further, the scarcity of high assay ore deposits has spawned a need for flotation reagents of improved selectivity.